Since the advent of rotatable cylindrical magnetron sputtering sources    PTL 0001: U.S. Pat. No. 4,356,073 (SHATTERPROOF GLASS CORPORATION). 1982 Feb. 26.
the use of dynamic seals on a rotating cylindrical target has been a common feature across this sector of the industry. Still today the state of the art involves the use of this type of dynamic seals for the driving (rotation) of the target    PTL 0002: US 2007/007129 (BEKAERT ADVANCED COATINGS). 2007 Jan. 11. and    PTL 0003: US 2008/0202925 (BEKAERT ADVANCED COATINGS). 2008 Aug. 28.
Existing solutions involving dynamic seals limit several aspects of the operation of such devices, like the air to vacuum, water to vacuum and water to air leak rates. Especially, with regard to leak rates into the vacuum process area, this can have a detrimental effect in the quality of the end product: that product being a plasma process such as coating deposition or plasma treatment. The use of dynamic seals also limits the maximum rotation speed of these targets as higher speeds tend to increase the leak rate into the vacuum media. In addition, lower target rotation speeds tend to increase the level of coating defects during the deposition process. This phenomenon is especially pronounced during so-called “reactive processes” whereby the target material reacts with the gases in the rarefied and/or partial vacuum and/or vacuum atmosphere in order to form a compound of a different nature to the target material itself. In non-reactive processes, a certain level of defects exists in the coating due to the reactivity of the target material with different outgassing elements of the deposition system and/or the target itself. All this can, in turn, create micro-arcing which can be responsible for a lowering in coating quality.
Existing solutions also limit the type of target construction that can be implemented and the ways in which changing the target (a process consumable) can be performed. Firstly, changing a target typically involves the opening of water-to-vacuum static seals which makes them very difficult to handle in very clean environments, such as those found in clean rooms in semiconductor manufacturing environments. Also, the known types of target construction, which use a static water-to-vacuum seal, introduce limitations in the way a target material can be manufactured, typically involving very expensive methods, especially if the purity of the target, its machinability and availability of the target material is complicated.
A need therefore exists for an alternative and/or an improved apparatus and/or method of driving a moveable element in a vacuum system from without the vacuum chamber.